I also will be keeping shutter speeds up, any suggestions. For the most part I want to shoot at the reciprocal of 400x1.6x(convertor if any) so for now it will be a min of 1/640s.

For the first time I will be shooting RAW ..... +jpeg (just in case)

Need to buy a circular polariser before I go.

Any other

Cheers
Andrew

I don't think the polariser is needed with the 400 f/5.6 unless you are doing some very tight landscape shots of things far in the distance. Mostly it will just cut down on your light and generally you will need all you can get. I think if you shoot from a car window or use a fence or log, a bean bag could be very useful. I agree the absolute minimum shutter speed should be 1/640 hand held, typically I do 1/1000 unless I really need to push it due to lack of available light. I don't have a 50D but I do have a 550D and 7D and I generally only go to ISO 1600 if I really need to. Conversely I almost never go below ISO 400 because there isn't much IQ difference from ISO 100-400. If you use a 1.4x teleconverter be prepared for a substantial drop in sharpness and contrast and either fully non-functioning autofocus (with official Canon TC's) or very unreliable autofocus with 3rd party TC's (like Kenko). If you have lots of light available stopping down a bit can help, mostly due to the increased depth of field that means more of a bird's body will be in focus. The 400 f/5.6 is a great lens overall and with the right light and technique one can produce outstanding photographs.